1 A4 sheet of blue foam 0.5mm thick,Sharp Xacto knife,Metal ruler,Hot glue gun, you could use PVA or wood glue but I found the hot glue was great as it dries solid pretty quickly and allows for easy construction.,

Probably with a general disclaimer at this point, Xacto knifes will be very sharp and they do glide through the foam with little resistance so it's very easy to cut through and has the potential to cause injury, on a similar theme the glue gun (if you use one) does get really really hot, as does the glue itself, you don't want to touch the metal heated element at the end of the glue gun to the foam as it will melt it and if it comes into contact with your skin you will burn yourself.

At the end of the basic construction of the project I was left with roughly a third of the blue foam left so in terms of material cost it was pretty cheap.

First 4 pics are as follows Materials I started with, Selection of cut foam parts that were then assembled, Angled pieces showing to what degree I cut them for the angled sections and then How I used the papercraft bits to make sure the angles were glued together in the right way.

next 4 show the progression of the construction for the project the first pic is the basic frame of the bunker, the second is with the roof on, the third is with the supports on the side and the forth is the same with the roof on.

So today I started working on the detail side of things the first thing you can see in picture one is that I cut an angle on the roof and also on the window ledges to make these less 'rigid', I thine added some magnets as per picture 2, pictures 3 and 4 show where I have liberally applied pollyfiller to the outside of the foam so as to create a better texture to paint on that i think also makes it look more realistic. I wasn't too concerned with rough edges at this point as I was planning to go over it all with some sandpaper anyway.

The first pic here was just to show how it looked after sanding and also how strong those diddy magnets were, I was only holding on to the roof and the pull on the magnets was enough to hold the rest of the bunker in the air. The second picture is after a coat of army painter uniform grey primer with the last two pic's showing the freehand aquilla on the roof and the shading / highlighting of chaos black / light grey.

just from ebay, was a couple of quid for 4 sheets, I used like 2 thirds of a sheet for the whole bunker. I think with some slight tweaking you could adapt the bunker design to make a sick looking wall / gateway to an imperial complex..... something for the future for me I thinking after the bastion / firebase and my eldar webway assembly building are out of the way.